Luxcore noisy render
I read that Luxcore was working as a camera so if the image is too dark you need to add more light in the scene or it gets noisy.


This is not correct. The brightness of the image does not matter.

To reduce noise, you have these options:


Render more samples
Use the denoiser (in the render settings, "LuxCore Denoiser" panel)
Optimize your scene so you get less noise with the same amount of samples, or more samples in the same amount of render time (this requires knowledge about the settings in your scene, so I can not help with this without the .blend file)